1. Field of the Invention
The present invention relates to a seat sliding apparatus for a vehicle seat having a walk-in mechanism.
2. Description of the Related Arts
In this kind of a seat sliding apparatus, a vehicle seat having a seat back, which can fold in a forward-and-backward direction, is mounted to an upper rail. The upper rail is slidably fitted into a lower rail fixed to a vehicle floor.
When the seat back is folded forward, a lock plate which obstructs the movement of the vehicle seat in the forward-and-backward direction is released by actuation of a walk-in mechanism, namely, the vehicle seat is moved to an unlocked position, and the vehicle seat is moved forward by force of a spring.
In addition, in order to prevent the lock plate from returning to the locked position at the time when the vehicle seat is moved forward, a memory mechanism section having an operation lever and a memory bracket is provided.
The operation lever is rotatably mounted to the upper rail by an axis fixing pin and a force is applied to the operation lever by a torsional spring and a draft spring installed between the upper rail and a lock pin of the lock plate so that the operation lever is biased to rotate in a clockwise direction.
When the seat back is folded forward, the operation lever is rotated by actuation of the walk-in mechanism in the counterclockwise direction against the spring force of the draft spring and presses down the lock plate. As a result, the locking portion of the lock plate is released and the vehicle seat is in an unlocked position in which it can move in the forward-and backward direction.
In addition, the memory bracket is rotatably mounted to the upper rail by an axis fixing pin and a force is applied to the memory bracket by a spring so that the memory bracket is biased in a counterclockwise direction. Thus, the operation lever and the memory bracket are biased to rotate in opposite directions.
When the seat section is moved from the forward moved position to a prescribed backed position, a memory holding pin, which is pushed through a slanted slide hole provided in the memory bracket and a horizontal slide hole provided in the upper rail, through cooperation of the operation lever and memory bracket can maintain the lock member in the lock-released state, namely, the vehicle seat can be maintained in the unlocked state.
The above-mentioned seat sliding apparatus is arranged so that the axis fixing pins which are mounted respectively to the operation lever and memory bracket are caulked and fixed to the upper rail, and dismounting of parts occasionally occurs at the time of the caulking step, so this apparatus has a problem of dissatisfactory assembly.